1. Field of the Invention
This invention relates to loose-leaf binders and methods of assembly thereof.
2. Brief Description of the Prior Art
Conventional plastic covered binders are typically comprised of a vinyl covering formed from two sheets in overlying relationship, that are divided transversely into two cover leaves and a central spine portion. Reinforcement, usually cardboard, is provided in each cover leaf, between the two vinyl plies, and a metal or cardboard backplate is inserted between the plies in the spine portion, to support a snap-action ring member, which is secured to the backplate with rivets.
When a vinyl cover of the above type having a metal backplate is manufactured, the backplate is inserted after the cover is fabricated. To facilitate this, a space or pocket for the metal backplate is preserved with a cardboard insert in the spine portion between the two plies.
When the two plies are sealed about the cover leaf reinforcements and between the cover leaves and the spine portion with a heat sealing mechanism, the temporary use of the nonconductive cardboard insert in place of the metal backplate prevents arcing or shorting of the electronic sealing machine used to seal the cover plies. This also avoids any damage to the vinyl that might otherwise be caused by sharp edges of the metal backplate when the vinyl plies in the hinge areas are pressed together for heat sealing. A slit is then made in the spine portion, usually across one end, to permit removal of the cardboard spacer and insertion of the metal backplate.
Cardboard backplates are sometimes used wherein the head of a conventional rivet is captured between cardboard plies to extend outwardly therefrom.
These constructions are disadvantageous, especially when it is considered that the binder is intended to be a low cost product, because the described backplates are relatively expensive and substantial labor and handling are required to both insert and remove the cardboard spacer and subsequently insert a metal backplate having extending rivets that stretch the plastic during insertion. Furthermore, the rivets used to attach the metal ring assembly against the spine portion require hand peening.
The prior art in this field is illustrated by several patents which disclose plastic binder constructions having various spine assemblies to which there are secured ring mechanisms.
Beyer, U.S. Pat. No. 3,809,485 discloses a plastic backbone or spine for a loose-leaf binder with integral studs for securing a ring member and separate abutments for inhibiting movement of the ring member along the backbone. In one embodiment the backbone is insertable as a separate member between plies of a binder cover. In another embodiment it forms an integral portion of a unitary plastic loose-leaf binder cover. The studs are headed, with a slot to allow deformation and insertion into apertures of a ring member. Upon localized heating of the heads, plastic flows into the slots to prevent removal of the ring member.
McKowen, U.S. Pat. No. 3,175,847 discloses a plastic spine construction having outer and inner spine members which are secured together by a post and perforation arrangement wherein connecting posts are headed, and the heads are snapped through the perforations to provide a permanent connection between the spine members. The binder cover members are provided with a back member that is interposed between the spine members. The inner spine member provides a base for a ring assembly.
Schade, U.S. Pat. No. 2,632,657 discloses a book binder constructed of plastic material comprising stiff cover sheet of a single thickness of plastic and a central spine assembly. The spine assembly comprises a sheet metal strip laminated between two sheets of flexible plastic. A pair of longitudinally spaced hollow rivets fastened to the strip extend through holes in the inner flexible sheet. The sheets are welded along the sides of the strip to form flexible hinges. The stiff cover sheets are welded to the hinges, a ring mechanism is inserted over the rivets, and the rivets are headed to form the finished binder.
Errichiello, U.S. Pat. No. 4,295,747 discloses a one piece molded binder having a plastic spine and front and rear plastic cover panels integrally molded with the spine and hingedly connected to the spine on its inner face by living hinges. The spine has a plurality of tubular posts on its inner face on which is secured a ring mechanism by drive or clinch rivets pressed into the tubular posts.
Libby, U.S. Pat. No. 3,201,145 discloses a molded looseleaf binder with built in hinges and flanges. The head of conventional rivets are molded into the material of the spine and their shanks extend through a base plate member. Transverse hole extend through the rivets and to receive rings which also pass through holes in the base plate member.
The prior art in general, and these patents in particular, do not disclose the novel looseleaf binder construction or the method of assembly of this invention.